indexed<Data> static method

SliverTreeView<Data, IndexedTreeNode<Data>> indexed<Data>({ Key? key, required TreeNodeWidgetBuilder<IndexedTreeNode<Data>> builder, required IndexedTreeNode<Data> tree, ExpansionBehavior expansionBehavior = ExpansionBehavior.none, Indentation? indentation, AutoScrollController? scrollController, ExpansionIndicatorBuilder? expansionIndicatorBuilder, ValueSetter<IndexedTreeNode<Data>>? onItemTap, EdgeInsetsGeometry? padding, bool showRootNode = true, bool focusToNewNode = true, TreeReadyCallback<Data, IndexedTreeNode<Data>>? onTreeReady, Animation<double>? animation, })

The alternate implementation of SliverTreeView uses an IndexedNode internally, which is based on the List data structure for maintaining the children states. The IndexedNode allows indexed based operations like insertion and removal of items at index positions. This allows for movement, addition and removal of child nodes based on indices.

The complexity for accessing child nodes in SliverTreeView.indexed is simply O(node_level ^ children). The main advantage of using a SliverTreeView over the TreeView is that it can be easily used with others slivers in a CustomScrollView, which means that you can easily implement a fancy animated list. The slivers are lazy loaded by default, so it can be easily mixed with other widgets without any loss of performance.

** See code in example/lib/samples/sliver_treeview/sliver_treeview_sample.dart **

See also:

• If you do not require index based operations, then use the more performant and efficient SliverTreeView.simple instead.
• For using an object that extends the IndexedTreeNode instead of using IndexedTreeNode directly, used the SliverTreeView.indexTyped which allows for typed objects to be returned in the builder

Implementation

static SliverTreeView<Data, IndexedTreeNode<Data>> indexed<Data>({
  Key? key,
  required TreeNodeWidgetBuilder<IndexedTreeNode<Data>> builder,
  required final IndexedTreeNode<Data> tree,
  ExpansionBehavior expansionBehavior = ExpansionBehavior.none,
  Indentation? indentation,
  AutoScrollController? scrollController,
  ExpansionIndicatorBuilder? expansionIndicatorBuilder,
  ValueSetter<IndexedTreeNode<Data>>? onItemTap,
  EdgeInsetsGeometry? padding,
  bool showRootNode = true,
  bool focusToNewNode = true,
  TreeReadyCallback<Data, IndexedTreeNode<Data>>? onTreeReady,
  Animation<double>? animation,
}) =>
    SliverTreeView._(
      key: key,
      builder: builder,
      tree: tree,
      expansionBehavior: expansionBehavior,
      indentation: indentation,
      expansionIndicatorBuilder:
          expansionIndicatorBuilder ?? _defExpansionIndicatorBuilder,
      scrollController: scrollController,
      onItemTap: onItemTap,
      padding: padding,
      showRootNode: showRootNode,
      onTreeReady: onTreeReady,
      focusToNewNode: focusToNewNode,
      animation: animation,
    );